Stainless iron base alloy metal-to-metal high speed seals

ABSTRACT

A highly corrosion and abrasion resistant stainless iron base alloy for metal-to-metal high speed seals consisting essentially of 3.1 to 3.65% carbon, 24 to 27% chromium, up to 0.9% manganese, up to 1.50% silicon and the balance iron.

United States Patent [1 1 Gobble et a1.

STAINLESS IRON BASE ALLOY METAL-TO-METAL HIGH SPEED SEALS Inventors:Glenn R. Gobble; Richard G. Loebs,

both of Peoria, 111.

Assignee: Caterpillar Tractor Co., Peoria, 111.

Filed: Mar. 22, 1974 Appl. No.: 453,846

Related U.S. Application Data Division of Ser. No. 299,103, Oct. 19,1972.

U.S. c1 75/126 A, 2 9 1 s 3 Int. Cl. C22c 39/141 Field of Search 75/126A; 29/183, 191

References Cited UNITED STATES PATENTS 11/1917 Becket ..75/126A PrimaryExaminer-L. Dewayne Rutledge Assistant Examiner-Arthur J. SteinerAttorney, Agent, or Firm-Phillips, Moore, Weissenberger, Lempio &Strabala [5 7] ABSTRACT A highly corrosion and abrasion resistantstainless iron base alloy for metaLtO-metal high speed seals consistingessentially of 3.1 to 3.65% carbon, 24 to 27% chromium, up to 0.9%manganese, up to 1.50% silicon and the balance iron.

2 Claims, No Drawings STAINLESS IRON BASE ALLOY METAL-TO-METAL HIGHSPEED SEALS This application is a division of application Ser. No.299,103 for Stainless Iron Metal-to-Metal High Speed Seals, filed Oct.19, 1972.

BACKGROUND OF THE INVENTION throughout industry because of theiroutstanding corrosion resistance under severe conditions. This property,coupled with wear resistance and other favorable metallurgicalproperties, has accounted for their increasing utilization. However,where such alloys have been subjected to extremely severe serviceconditions, e.g., the presence of mud and dirt, and wherein such alloysare used to form seals to protect vital machinery parts, it has beenfound necessary to resort to stainless steels having even morepronounced wear and corrosion resistance.

In order to achieve such wear and corrosion resistance, the industry hashad to resort to alloy stainless steels including costly alloyingelements such as columbium, cobalt, molybdenum and vanadium. Such alloyshave been found to be highly suitable for such severe service use.However, it has been found desirable from both an economic standpointand from a strategic availability" standpoint to develop alloys suitablefor such severe service use, but wherein such elements as vanadium,molybdenum, cobalt, and columbium are unnecessary.

A stainless iron base alloy has now been developed which is totally freefrom such exotic elements, but which exhibits comparable properties ofwear and corrosion resistance. At the same time, the brittlenesscharacteristics of the alloy are sufficiently low to obviate thenecessity of careful handling during casting and subsequent operations.Such alloy comprises relatively high amounts of chromium and carbonwhich are alloyed in an iron base together with small percentages ofmanganese and silicon. Such stainless alloy differs from known stainlesssteel alloys possessing similar corrosion and wear resistantcharacteristics in that the more exotic materials such as molybdenum,cobalt, vanadium and columbium are eliminated, yet the alloy possessesconveniently low brittleness characteristcs. This resultant alloy is aneconomical metallurgical composition which still exhibits the requiredcharacteristics for severe service use.

BRIEF SUMMARY AND OBJECTS OF THE INVENTION The present invention is astainless alloy, suitable for metal-to-metal face seals and likestructures, wherein said alloy comprises a relatively large percentageof chromium, a lesser amount of carbon, and even smaller amounts ofmanganese and silicon, all alloyed with a major percentage of iron.

It is therefore, and object of the present invention to provide astainless alloy having outstanding wear and corrosion resistantcharacteristics.

It is another object of the invention to provide a stainless alloy fromwhich all exotic elements such as molybdenum, vanadium, columbium, andcobalt are eliminated.

It is still another object of the invention to provide a stainless alloycomposition comprising iron, chromium, carbon, silicon and manganesehaving excellent wear and corrosion resistant characteristics, andcomparatively low brittleness characteristics.

It is a further object of this invention to provide an alloy suitablefor severe service conditions but comprising readily available andinexpensive alloying elements.

It is still a further object of the invention to provide a stainlessalloy having excellent wear and corrosion resistance when utilized inmetal-to-metal constructions involving both high and low speed relativemotion between parts.

DETAILED DESCRIPTION OF THE INVENTION The alloy of the present inventioncomprises a material exhibiting the properties of a wear-resistant,stainless steel wherein said properties are derived from a combinationof the elements iron, chromium, carbon, manganese, and silicon. Inaccordance with this invention, a stainless iron base alloy is providedhaving the following percentages (by weight) of these elements:

Carbon 3.l() 3.65 Chromium 24 27 Manganese 0.90 (maximum) Silicon L(maximum) Iron Balance The presence of chromium in the above stainlessalloy imparts excellent corrosion resistance thereto. Preferably, thechromium percentage in the alloy is about 25 percent to impart optimumabrasion and corrosion resistance.

The carbon in the alloy forms intermetallic carbides which are dispersedthroughout the solid solution of chromium-iron; these carbides impartexcellent wear resistant properties to the alloy. .It is preferable thatcarbon be present in the alloy in an amount of about 3.5 percent toobtain optimum wear resistance with minimal brittleness characteristics.This property of carbon which imparts brittleness to the stainless alloyI of the invention requires that the percentage of carbon in thecomposition not exceed that indicated above, i.e. 3.65 percent, lest thealloy be too brittle for usefulness. Within the ranges specified, thehigh carbon alloy exhibits greatly superior wear characteristics overconventional stainless alloys, especially in high-speed applications.Further, such alloys have conveniently low brittleness characteristicswhich do not require special handling during casting or subsequentoperations. These alloys are excellent for use in high-speedmetalto-metal seal construction.

Manganese and silicon are added to control depth of chill and hardness,inter alia. The ranges specified above contribute to an excellent wearand corrosion resistant alloy in conjunction with the specified amountsof carbon, chromium and iron. Preferably, manganese is present inamounts of about 0.5 percent by weight in the alloy of the invention.

Iron is of course the predominant element in the alloy, and in thepresence of the amounts of chromium indicated above, forms a solidsolution therewith having excellent corrosion and stain resistantproperties.

The alloys of the invention can be produced by metallurgical alloyingtechniques commonly practiced in the art. The alloy furnishes anexcellent material for the production of cast products wherein extremehardness and outstanding stain resistance are desirable, in particularcast seals such as those described in U.S. Pat. No. 3,180,648 to Kupfertet al., filed Dec. 14, 1959, and having common assignee herewith.

For example, cast seals having an alloy composition of this inventionwere produced by conventional shell molding techniques. After thecasting were cleaned, they were heated to 1,850 to 1,900 F for one hour,followed by air-quenching to room temperature, and

' then tempered by reheating to 375F for one hour. The

castings had a through hardness of Rockwell C63 and displayed anunexpectedly high transverse rupture strength.

Equally good results were obtained by forming castings of seals of thealloy of this invention by the flexible pattern techniques disclosed inUS. Pat. Nos. 3,552,480 (Harris) and 3,570,585 (Harris), for example,followed by heating, quenching, and tempering as noted above. Inaddition, such ring seal castings exhibited Rockwell C hardnesscomparable to stainless steel alloys containing large amounts of exoticmaterials such as molybdenum, cobalt, and vanadium.

What is claimed is:

1. In stainless iron base metal-to-metal high speed seal constructionsthat include at least two face-to-face metal surfaces and wherein saidsurfaces are movable relative to each other, an alloy forming saidsurfaces consisting essentially of 3.1% to 3.65% carbon, 24% to 27%chromium, up to 0.9% manganese, up to 1.50% silicon, and the balanceiron.

2. The stainless iron base metal-to-metal high speed seal constructionof claim 1 wherein said face-to-face metal surfaces are formed of analloy consisting essentially of about 3.5% carbon, about 25% chromium,about 0.3% manganese, about 0.5% silicon, and the balance iron.

1. IN STAINLESS IRON BASE METAL-TO-METAL HIGH SPEED SEAL CONSTRUCTIONSTHAT INCLUDE AT LEAST TWO FACE-TO-FACE METAL SURFACES AND WHEREIN SAIDSURFACES ARE MOVABLE RELATIVE TO EACH OTHER, AN ALLOY FORMINGSAIDSURFACES CONSISTING ESSENTIALLY OF 3.1% TO 3.65% CARBON, 24% TO 27%CHROMIUM, UP YO 0.9% MANGANESE, UP TO 1.50% SILICON, AND BALANCE IRON.2. The stainless iron base metal-to-metal high speed seal constructionof claim 1 wherein said face-to-face metal surfaces are formed of analloy consisting essentially of about 3.5% carbon, about 25% chromium,about 0.3% manganese, about 0.5% silicon, and the balance iron.